Switch



Jan. 4, J, w A K r I SWITCH Filed Jan. 21, 1943.

INVENTORS JOHN VABUSACKER BY THO RRYM$ A TORIk Patented Jan. 4, 1949 UNITED EN T O F-F ICE SWITCH JphmWIBusacker; Houston}: Tex.,;and; Thomas Perry,f'B enni ngton,- Vt; assignors' t(r-the "United States f Americar asrepresented by the -'Secretary of the' Nayy Application Janua y 21,;1fi43, .Seria'LNo. 473,148

This inyentionrelates to switches and more particularly .to.a so-ca11ed unshorting switch of novel construction for normally short-circuiting an electrical-deviceand operable by a force of set-back to remove the short circuit. The new switch is simple and compact inconstruction and positive in operation. 7 1

While-:the invention is-suitedz-for various uses, it may be employed to particular advanta e as a although it willbe understood'that the invention maketake other forms .as well.

.One' object of the invention residesin'the-pro vision of a novel unshorting switch of simple and rugged construction adapted for manufacture at low cost, which is operable by a force of set-back to remove the shortcircuit.

Another object of the invention is to provide a switch of the character described in which the short-circuiting element maintains an inertia member in an inoperative position under normal conditions but is broken by the member when the latter is subjected to a relatively heavy force, such as that due to the force of set-back incident to firing a projectile from a gun.

These and other objects of the invention may be better understood by reference to the accompanying drawing, in which Fig. 1 is a longitudinal sectional view of part of a projectile, showing schematically one use of the switch in the detonating circuit of the projectile;

Fig. 2 is a longitudinal sectional view of one form of the new switch, showing the inertia member in its inoperative position;

Fig. 3 is a view similar to Fig. 2 but showing the inertia member after it has broken the shortcircuiting member in response to a force of setback;

Fig. 4 is a plan view of the switch shown in Figs. 2 and 3, and

Fig. 5 is a perspective view of a modified form of the switch.

In the drawing, the unshorting switch I0 is shown mounted in the casing of a projectile H containing a detonating squib I2 for exploding the main charge (not shown) in the projectile. The squib is of the electrical type and is adapted to be operated by a fuze [3 connected in series with the squib through wires Hi to form a detonating circuit. Any desired form of fuze may be employed. such as a time-operated fuze or a fuze (Cli 200' 52) H 2 responsive to proximity ;of anairplane or other ;-target. The switch I8; is connected between-the wires""l4 by conductors "I 5 so that it normally short-circuits thesquib l2, the electrical resist- 5 ances ;of-t he switch and the squibbeing so proportioned 'that 'the current normally flowing through the sguib'is insufficient tooperate it.

' "The switch l 0,-as' shown, comprises a cylindrical body itimade of inslllating material, such as 1 lucite, and having a recess" in its rear endp or- --tion. An axial bore -18 extends from the recess "'11-- through thefrontend of the body. Mounted on'-the the-front end of-the body are twodi- ---ametrically'--opposed;terminal plates 19 and--20, formed-of brass-orother suitable metal, the'plates being secured ;-tothe body by pins 2 l. The terminal platesl fiandfifi are provided with terminal screws 22 and 23, respectively, to which the shunt wires l 5 may be joined for connecting the switch across the squib l2.

A. short-circuiting wire 24 extends between the terminal plates l9 and 20 and is connected thereto in any suitable manner, as by means of solder spots 24a. The wire 24 extends through a 25 passage 25 in the front end portion of a plunger 26 slidably mounted in the bore l8. As shown, the front end of the plunger projects from the bore I8 between the terminal plates l9 and 20,

and the rear end of the plunger projects into the 30 recess IT. The weight of the plunger and the tensile strength of the short circuiting wire 24 are so proportioned that the wire is adapted to hold the plunger in its inoperative position (Fig. 2) under normal conditons, as, for example, during handling and loading of the projectile.

In the operation of the new switch, when the projectile l I is fired from a gun, the force of setback incident to acceleration of the projectile in the gun barrel causes the plunger 26 to move rearwardly in the bore I8 into the recess I1. As a result, the force of the plunger overcomes the tensile strength of the wire 24 and breaks th wire, as shown in Fig. 3, so as to remove the shortcircuit of the squib I2 and arm the detonating circuit. The squib is then prepared for operation under control of the fuze I3.

The switch shown in Fig. 5 is similar to that shown in Figs. 2 to 4, inclusive, except that means are provided for supplementing the short-circuit- 5O ing wire 24 to hold the plunger normally in its inoperative position. More particularly, the plunger 26a is provided on its forward end with a knob 28 partly defining an annular groove 28a to the rear of the knob. A post 253 is mounted on the front end of the switch body it adjacent the Wire plunger and is formed with a circumferential groove for receiving the looped end of a retaining 38 in any drop or jolt test, but said spring will I be unable to absorb the accumulated'forces of acceleration in the gun bore, with the result that, as the projectile is fired from a gun, the force of set-back causes the plunger 26a to disengage the retaining wire 30 which snaps out of the groove 28a. At the same time, the plunger breaks the short-circ'uiting wire 24 andmoves to the rear into recess 57, whereby the short-circuit is removed.

It will be apparent that the new switch provides'a reliable safety means for preventing premature operation of the detonating squib l2.

Accidental actuation of the switch by the plunger is efiectively prevented by reason of the close fit of the plunger in the bore l8 and because of: the

inherent tensile strength inthe short-circuiting The switch includes only a single moving part and may be madein a compact form; and by making the body 16 of cylindrical shape, the switch may be easily fitted in the usual cylindrical chamber in theprojectile casing so that it:oecu- 35 pies a relatively small space. Thewire 24 serves the dualfunction of a short-circuiting element and a means for retaining the inoperative position.

We claim:

1. An unshorting switch comprising a short circuiting wire, a retainer'adjacent the wire, and a plunger connected to the wire and the retainer and normally held thereby in an inoperative position, the plunger being operable by a force of setback to break the retainer and the wire.

'2. In combination with a projectile, an un shorting switch including an insulating body having'a bore, a pair of terminals on the body, a short-circuiting wire connecting the terminals and extending across the bore, and an inertia member movably mounted in the bore and receiving the short-circuiting wire therethrough,

said intertia member being displaced by set-back forces incident tothe discharge of the projectile for breaking the wire.

JNO. W. BUSACKER. T. M. PERRY.

- REFERENCES CITED The following references are of record in the file of this patent:

, -UNITVED STATES PATENTS Number Name Date 1,890,445 -Asire et al. Dec.. 13, 1932 1,975,809 Feitscheid p Oct. 9, 1934 2,105,288 I Jennings Jan. 11, 1938 I FOREIGN PATENTS Number Country Date 91,592 Sweden Feb. 24, 1938 plunger in its 

